Field of the Invention
This invention relates generally to improvements in infusion pumps of the type used for controlled delivery of medication to a patient. More specifically, this invention relates to an improved infusion pump designed to receive and support a medication-containing syringe in one of two different selected positions.
Infusion pump devices and systems are relatively well known in the medical arts, for use in delivering or dispensing a prescribed medication such as insulin to a patient. In one form, such devices comprise a relatively compact pump housing adapted to receive a syringe carrying a prescribed medication for administration to a patient through infusion tubing and an associated catheter or the like. The infusion pump includes a small drive motor connected via a lead screw assembly for motor-driven advancement of a syringe piston plunger to administer the medication to the patient. Programmable control means are normally provided for operating the drive motor continuously or at periodic intervals to obtain a closely controlled and accurate delivery of medication over an extended time period. Such infusion pumps are utilized to administer insulin and other medications, with an exemplary pump construction being shown and described in U.S. Pat. Nos. 4,562,751 to Nason et al., 4,678,408 to Nason et al, and 4,685,903 to Cable et al. U.S. Pat. Nos. 4,562,751, 4,678,408, and 4,685,903 are hereby incorporated herein by reference.
Infusion pumps of the general type described above have provided significant advantages and benefits with respect to accurate delivery of medication over an extended time period. The infusion pump is often designed to be extremely compact and may thus be adapted to be carried by the patient, for example, by means of a belt clip or the like. As a result, important medication can be administered with precision and in an automated manner, without significant restriction on the patient's mobility or life-style.
To achieve accurate and reliable delivery of medication to the patient in response to motor-driven advancement of a syringe piston plunger, it is extremely important for the associated syringe barrel to be secured or locked in place within the pump housing. Otherwise, inadvertent displacement of the syringe barrel toward the piston plunger can result in undesired excess medication delivery. Conversely, inadvertent displacement of the syringe barrel away from the piston plunger can result in undesired nondelivery of medication upon subsequent advancement of the piston plunger.
More specifically, as shown in U.S. Pat. Nos. 4,562,751, 4,678,408, and 4,685,903, one relatively simple arrangement for securely locking the syringe barrel includes the formation of a narrow profile luer neck connected between the barrel and a luer fitting at a nose end of the syringe. This reduced profile neck is adapted to seat within a matingly sized outlet port defined by the pump housing, such that the housing at said outlet port provides an effective lock member engaged axially between the syringe barrel and luer fitting. As a result of this axial engagement, the syringe barrel is securely seated or locked relative to the pump housing.
However, this locking arrangement positions the luer fitting on the exterior of the pump housing where it effectively increases the overall size and length of the infusion pump. In an effort to reduce the pump length and size, some patients attempt to mount the syringe with the luer fitting recessed into the pump housing at the inboard side of the outlet port. Unfortunately, in this recessed position, the infusion pump lacks structural means for preventing undesired displacement of the syringe barrel toward the piston plunger. Such undesired displacement can occur due to inadvertent bumping of infusion set components, resulting in undesirable and uncontrolled delivery of a medication bolus to the patient.
There exists, therefore, a significant need for an improved infusion pump adapted for securely supporting the barrel of a medication-containing syringe in either one of two different mounting positions, thereby permitting a luer fitting at the nose end of the syringe to be positioned outside or alternately recessed into the pump housing. The present invention fulfills these needs and provides further related advantages.